This invention is directed to the formation of one or more channels into the wall of a patient's heart and particularly to a system for securing the optical fiber system while forming the channel in the patient's heart wall.
The channels formed in the wall of the patient's heart may be used in the treatment of heart tissue experiencing ischemic conditions by allowing increased perfusion of blood through the channel into the myocardium of a patient's heart. The formation of channels into the myocardium for improved perfusion into a patient's ischemic myocardial tissue is called myocardial revascularization. The first clinical trials of the revascularization process was made by Mirhoseini et al. See for example the discussions in Lasers in General Surgery (Williams & Wilkins; 1989), pp 216-223. Other early disclosures of this procedure is found in an article by Okada et al. in Kobe J. Med. Sci 32, 151-161, October 1986 and U.S. Pat. No. 4,658,817 (Hardy). These early references describe intraoperative revascularization procedures which require an opening in the chest wall and include formation of the channels through the epicardium.
Copending application Ser. No. 08/368,409, filed on Dec. 30, 1994 (Aita et al.), which is incorporated herein in its entirety, describes a percutaneous system for myocardial revascularization which is introduced through the patient's peripheral artery. The channels are formed through the endocardium into the myocardium. The channels formed in the ventricular wall may also be used for delivery of therapeutic or diagnostic agents, including agents for gene therapy.
While the percutaneous system for performing revascularization, developed by Aita et al., was a substantial advance, one of the difficulties found in forming the channel from within the patient's heart chamber was maintaining the distal end of the optical fiber against the endocardial wall. Apparently, acoustic energy created by the absorption of the laser energy emitted from the distal tip of the optical fiber system by the surrounding fluid, i.e. blood, can cause the distal end of the optical fiber system to be laterally displace away from the region of the endocardial surface in which the channel is to be formed. The distal tip of optical fiber tends to "skip" along the surface of the endocardial wall, thereby disabling channel formation. In European application Publication No. 0 515-867 A2 (Jeevanandam et al.) reference is made to providing suction means on a catheter into which the optical fiber system is slidably disposed to hold the position of the assembly adjacent to the ventricular wall. While this provides some benefit, it does not ensure that the distal tip of the optical fiber will remain in place when laser energy is transmitted to the tissue of the ventricular wall.